Effect of Ambient Gas and Temperature on Crystallization of Boron Nitride Spheres Prepared by Vapor Phase Pyrolysis of Ammonia Borane

Abstract

Synthesis of boron nitride spheres (BNS) was achieved by vapor phase pyrolysis of ammonia borane (BH 3 NH 3 ) using two independently temperature-controlled furnaces in a glove box filled with N 2 . The BNS were heated at 13001-17001C in flowing NH 3 , N 2 , or Ar by multistep heat treatment. The sizes of the BNS could be controlled by heating BH 3 NH 3 at different rates (11C/min: 300-800 nm, 51C/min: 300 nm-1.2 lm and 101C/ min: 300 nm-1.8 lm). The microstructures of BNS heated in different ambient gases were observed using transmission electron microscopy with selected area electron diffraction. NH 3 gas produced BNS with well-crystallized surface shells and amorphous cores whereas N 2 and Ar gases crystallized the entire BNS. It is evident that of these three ambient gases (NH 3 , N 2 , and Ar), N 2 gas significantly enhances the crystallization of BN with randomly oriented grains.

Synthesis of large single-crystal hexagonal boron nitride grains on Cu–Ni alloy

“…20,36). The reactions involved suggest that the nanoparticles are most likely a complex mixture of poly-aminoborane and its partially dehydrogenated derivatives, consistent with earlier reports 23,24,26,41 and our Auger investigations (Supplementary Fig. 3a-e).…”

Ammonia borane: A high capacity chemical hydrogen storage material

“…除了作为储氢材料, 氨硼烷还在以下几个方面 有广泛应用: (1) 还原剂, 把醛、酮羰基还原为醇 [48] , 在有异丙醇钛的情况下, 把醛和酮还原胺化为伯胺、 仲胺、叔胺, 产率为 84%~95% [135] , 还可以把 CO 2 还 原为甲醇 [136] 等; (2) 在材料领域用于制备 BN 材料, 如 BN 管 [137,138] 、BN 球 [139] 、制备白色石墨烯 [140] 等;…”

Preparation and high catalytic performance of hollow BN spheres-supported Ni for hydrogen production from methanol

“…[9][10][11][12][13][14][15][16] Currently, there are only a few reports on the preparation of hollow BN spheres (HBNS). 6,[17][18][19] Since HBNS are usually produced from oxides or organic precursors, such as H 3 BO 3 and N,N-dimethylformamide, 17 the BN samples tend to contain O and C impurities. The use of a precursor without O and C as a starting material for preparation of BN is desired.…”

“…We previously reported the preparation of BN nanotubes, nanobamboos, nanofibers, and spheres with controlled sizes using an ammonia borane complex (BH 3 NH 3 ) as a starting material. 7,8,19 In a previous study, 19 it has been demonstrated that BN spheres composed of a crystallized shell and an amorphous core (core-shell BNS) are produced in NH 3 at high temperatures (>1300 C) by heating amorphous BN spheres (a-BNS) formed from BH 3 NH 3 . Hot H 2 O can dissolve a-BN but not crystallized BN.…”